Blog · Urgent Care March 2026 · 2 min read

UTI vs. kidney infection: how to tell the difference, and when to see a doctor

Burning when you urinate is never fun. But it matters whether you have a simple bladder infection, or something more serious happening in your kidneys.

UTI vs. kidney infection: how to tell the difference, and when to see a doctor

What a UTI is

A urinary tract infection is a bacterial infection anywhere in the urinary tract, most commonly the bladder. UTIs are among the most common infections in adults, affecting roughly 50 to 60% of women at some point in their lives.

Classic bladder UTI symptoms:

·Burning or pain when you urinate
·A frequent urge to urinate, even when little comes out
·Cloudy or foul-smelling urine
·Pelvic discomfort or pressure
·Possibly blood in the urine

Importantly, a simple bladder UTI typically does not cause fever, chills or back pain.

What a kidney infection is

A kidney infection happens when bacteria travel from the bladder up to one or both kidneys. This is more serious and needs prompt treatment — usually stronger antibiotics, and sometimes intravenous treatment in hospital.

Symptoms that point to a kidney infection rather than a bladder UTI:

·Flank pain — in your side and back, below the ribs
·Fever and chills, above 100.4°F
·Nausea or vomiting
·A general feeling of being very unwell
·Plus the UTI symptoms above
Go to the ER, not a screen
High fever above 103°F
Severe flank pain
Unable to keep fluids down
Pregnancy

Can a virtual visit treat it?

For most uncomplicated bladder UTIs, yes. A $39 quick care visit takes your history and symptoms, and if a UTI is the likely diagnosis, an antibiotic goes straight to your pharmacy.

For a suspected kidney infection, your physician will assess severity. Mild cases can sometimes be treated with oral antibiotics, but more severe ones warrant in-person evaluation and sometimes intravenous antibiotics. If that is what your answers suggest, you will be told plainly and refunded.

Can a kidney infection be treated at home?

Mild cases sometimes can, with oral antibiotics and close follow-up. Anything more severe — high fever, vomiting, severe pain — needs in-person assessment.

How quickly does a bladder UTI become a kidney infection?

It varies, and most UTIs never do. But an untreated bladder infection can progress within days, which is why it is worth treating promptly rather than waiting it out.

Lilit Margaryan, MD
Lilit Margaryan, MD, DABOM
Board-certified in Internal Medicine and Obesity Medicine. Founder of Li Health.

This article is general health information, not medical advice for your situation, and does not create a physician-patient relationship. If you are unwell, speak with a physician.

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